The present invention relates in general to energy absorbing systems, and more specifically to energy absorbing systems and articles having auxetic structures.
Energy absorbing systems broadly find application in many situations where excess energy needs to be managed, without causing damage to surrounding objects. For example, in the automotive industry, such systems are also referred to as Energy Absorbers (EA) and find an application in bumper systems of cars and the like. Typically, bumpers are designed to absorb most of the impact in case of collisions with other objects, including vehicles, stationary objects or pedestrians, to minimize damage to the passengers and the pedestrians. Conventionally energy absorbers have been manufactured using expanded foam or thermoplastic materials attached to a metal beam. The energy absorbers used in bumpers are required to provide safety-enhancing levels of energy absorption for collisions at impact speeds of about 40 km/hour and to minimize potential damage to pedestrians in low speed collisions between vehicles and pedestrians. Further, compliance with industry regulations, for example the need to provide adequate deformation in low speed collisions to minimize potential damage to pedestrians, and to provide a high barrier force in case of high speed impact, presents significant challenges to conventional metal or plastic bumpers. Further, modern energy absorbing systems must cope with complex situations such as multiple impact collisions wherein a second impact occurs on a previously deformed bumper. Typical energy absorbers (EA) occupy large volumes, which in some cases, is undesirable due to vehicle styling trends such as “low-offset bumpers”.
To meet today's rigorous safety standards while satisfying the requirements of current vehicle styling trends there exists a need for energy absorbing systems which are lightweight and low volume, and which provide better resistance to deformation and higher collision impact energy absorption than currently available energy absorbing systems. In general, there exists a need for energy absorbing systems capable of absorbing more energy at a lower mass, both within automotive applications and non-automotive applications.